Nasal cannula assembly with flow control passage communicating with a deformable reservoir
The invention concerns a nasal cannula assembly ( 10 ) adapted to deliver gases to a patient comprising a first compartment ( 1 ) and a second compartment ( 2 ) separated by a separation wall ( 6 ); a pair of nasal prongs ( 5 ) in fluid communication with the first compartment ( 1 ); the first compartment ( 1 ) comprising a first inlet ( 11 ) for introducing a first gas into said first compartment ( 1 ); the second compartment ( 2 ) comprising a second inlet ( 2 ) for introducing a second gas into said second compartment ( 2 ); and the separation wall ( 6 ) comprising at least one flow restriction element ( 35 ) for controlling the passage of gas from the second compartment ( 2 ) to the first compartment ( 1 ).
1. A nasal cannula assembly ( 10 ) adapted to deliver gases to a patient, the nasal cannula assembly ( 10 ) comprising:
a) a first compartment ( 1 ) and a second compartment ( 2 ) separated by a separation wall ( 6 ),
b) a pair of nasal prongs ( 5 ) in fluid communication with the first compartment ( 1 ),
c) the first compartment ( 1 ) comprising a first inlet ( 11 ) configured to conduct a first gas into said first compartment ( 1 ),
d) the second compartment ( 2 ) comprising a second inlet ( 12 ) configured to conduct a second gas into said second compartment ( 2 ), and
e) the separation wall ( 6 ) comprising at least one flow restriction channel ( 35 ) configured to
permit a passage of gas from the second compartment ( 2 ) to the first compartment ( 1 ) in a reduced pressure state during an inhalation phase and
prevent a majority of flow of the second gas from the second compartment ( 2 ) to the first compartment ( 1 ) in a higher pressure state, during an exhalation phase, relative to the passage of gas during a reduced pressure state, during an inhalation phase,
wherein the separation wall ( 6 ) comprises at least two flow restriction channels ( 35 ), and wherein the at least two flow restriction channels ( 35 ) are arranged in the separation wall ( 6 ), directly opposite the pair of nasal prongs ( 5 ).
2. The nasal cannula assembly according to claim 1 , wherein the first compartment ( 1 ) comprises the first inlet ( 11 ) forming a side gases entry in fluid communication with a gas transport conduct.
3. The nasal cannula assembly according to claim 1 , wherein the nasal cannula assembly further comprises a hollow body ( 4 ) comprising an internal chamber ( 7 ) comprising at least the first compartment ( 1 ).
4. The nasal cannula assembly according to claim 1 , wherein at least the first compartment ( 1 ) is part of a hollow body ( 4 ) configured to be capable of acting as a gas conduct or a gas manifold.
5. The nasal cannula assembly according to claim 1 , wherein a hollow body ( 4 ) and said pair of nasal prongs ( 5 ) are integrally molded from a soft plastics material.
6. The nasal cannula assembly according to claim 1 , wherein the pair of nasal prongs ( 5 ) are detachable from a hollow body ( 4 ) and selected from different sized prongs suitable for different sized patient nares.
7. The nasal cannula assembly according to claim 1 , wherein the at least two flow restriction channels ( 35 ) connect the first compartment ( 1 ) and second compartment ( 2 ) and are rounded edged at an entrance from the second compartment ( 2 ) and have a reentrant aperture at an entrance from the first compartment ( 1 ).
8. The nasal cannula assembly according to claim 1 , wherein the second compartment ( 2 ) comprises a deformable wall ( 14 ).
9. The nasal cannula assembly according to claim 1 , wherein the second compartment ( 2 ) forms a deformable-wall reservoir comprising a fully inflated internal volume for the gas of about 0.5 to 5 ml.
10. The nasal cannula assembly according to claim 1 , wherein the nasal cannula assembly does not comprise a sensor configured to detect an onset of patient inspiration.
11. The nasal cannula assembly according to claim 1 , wherein the at least two flow restriction channels ( 35 ) prevent the majority of flow of the second gas from the second compartment ( 2 ) to the first compartment ( 1 ) in the higher pressure state, during an exhalation phase, relative to the passage of gas during the reduced pressure state, during an inhalation phase.
12. The nasal cannula assembly according to claim 1 , wherein the at least two flow restriction channels ( 35 ) prevent >70% of flow of the second gas from the second compartment ( 2 ) to the first compartment ( 1 ) in the higher pressure state, during an exhalation phase, relative to the passage of gas during the reduced pressure state, during an inhalation phase.
13. The nasal cannula assembly according to claim 1 , wherein the at least two flow restriction channels ( 35 ) prevent >90% of flow of the second gas from the second compartment ( 2 ) to the first compartment ( 1 ) in the higher pressure state, during an exhalation phase, relative to the passage of gas during a reduced pressure state, during the inhalation phase.
14. The nasal cannula assembly according to claim 8 , wherein the deformable wall ( 14 ) of the second compartment ( 2 ) has a greater compliance while filling than when the second compartment ( 2 ) is full.
15. The nasal cannula assembly according to claim 1 , wherein the pair of nasal prongs ( 5 ) includes an external pillow element ( 8 ) at an end.
16. The nasal cannula assembly according to claim 15 , wherein said pillow element ( 8 ) is made of silicone.
17. The nasal cannula assembly according to claim 1 , further comprising one or more orifices ( 13 ) in the first compartment ( 1 ) defining a fluid communication from an internal chamber ( 7 ) to an external atmosphere.
18. The nasal cannula assembly according to claim 7 , wherein a diameter of each of the at least two flow restriction channels ( 35 ) is between 0.1 mm and 5 mm, and the rounded edges at an entrance to the at least two flow restriction channels ( 35 ) are designed such that the ratio between a radius of curvature of the rounded edges and the diameters of each flow restriction channel ( 35 ) is greater than 0.02.
19. A nasal cannula assembly ( 10 ) adapted to deliver gases to a patient, the nasal cannula assembly ( 10 ) comprising:
a) a first compartment ( 1 ) and a second compartment ( 2 ) separated by a separation wall ( 6 ),
b) a pair of nasal prongs ( 5 ) in fluid communication with the first compartment ( 1 ),
c) the first compartment ( 1 ) comprising a first inlet ( 11 ) configured to conduct a first gas into said first compartment ( 1 ),
d) the second compartment ( 2 ) comprising a second inlet ( 12 ) configured to conduct a second gas into said second compartment ( 2 ), and
e) the separation wall ( 6 ) comprising at least one flow restriction channel ( 35 ) configured to
permit a passage of gas from the second compartment ( 2 ) to the first compartment ( 1 ) in a reduced pressure state during an inhalation phase and
prevent a majority of flow of the second gas from the second compartment ( 2 ) to the first compartment ( 1 ) in a higher pressure state, during an exhalation phase, relative to the passage of gas during a reduced pressure state, during an inhalation phase,
wherein the second compartment ( 2 ) forms a deformable-wall reservoir comprising a fully inflated internal volume for the gas of about 0.5 to 5 ml.